1. Field of the Invention
This invention relates to a brake release device for a door machine, more particularly to a brake release device attached to an ordinary door machine in such a manner that the door machine is promoted a function as a door machine for a fireproof door.
2. Background Art
A door machine that is generally employed, for example, in a vertically lifted rolling door or a garage door, comprises at least a brake device for braking the door machine so as to maintain the rolling door or the door slats at a specified or a stationary position. This type of brake device, for example, is described in U.S. Pat. No. 7,341,129 granted to the Applicant, which mainly comprises a support frame having a plurality of guiding bars; a first braking pad guided by the guiding bars so as to be movable in an axial direction of the door machine axle; a second braking pad provided at the end portion of the guiding bars; a braking component including an axle-connecting portion and a brake disc; a spring component; a compression spring for pushing the first braking pad against the braking component toward the second braking pad; and an electromagnet configured to retract the first braking pad so as to disengage said first braking pad from the braking component, thereby releasing the brake device. The brake device further comprises a manual release mechanism including a U-shape portion and a pull bar. The manual release mechanism is pivotally disposed on the second braking pad through two tail ends of the U-shape portion. The pull bar is provided outside the door machine for operating the manual release mechanism to release the brake.
The door machine employed on the vertically lifted rolling door, the garage door or safety door is basically designed for the purpose of protecting humans' lives, while the door machine used on the fireproof door is basically designed for protecting the safety of equipments and properties. Hence, theses two types of door machine have different functions and can not be used in common. In order to meet different requirements on the market, the pertinent industries have to develop at least two door machines having different types of control. Hence, development proceedings are time-consuming and costly. Further, the manufacturing is complicated due to large number of parts, and thus inventory cost is high.
Another Applicant granted U.S. Pat. No. 7,610,719 discloses a brake release device attached to a door machine which allows the general door machine to possess a function as a door machine for a fireproof door. The brake release device is attached to the door machine, comprising a first electromagnet, when energized, a sliding portion of which can slide to actuate a sliding bar; a first and a second actuator, in which the first actuator is located to abut against the brake release bar of the door machine, and a sliding pin of the first actuator is yieldingly biased in the anti-activation direction of the bar, and the second actuator is limited by a limited means at a fixed position; a second electromagnet, when energized, used to release the second actuator; a circuit including a limit switch for transiently supplying power to the first electromagnet upon resetting of the device; and a capacitor for temporarily supplying power to the second electromagnet in an event of unexpected electricity failure. Thus, in the instant of unexpected electricity failure, the brake release device can release the brake by a mechanical force, and shut off the safety door by the sliding-down of its own weight.
In addition to the above, a number of documents have proposed the door machine of fireproof door, and some examples of which are U.S. Pat. No. 5,203,392, U.S. Pat. No. 5,386,891, and U.S. Pat. No. 5,355,927.